by Kevin Johnson, USA TODAY

by Kevin Johnson, USA TODAY

WASHINGTON - Federal lawmakers began debating Thursday - not whether, but how - the government's disputed surveillance authority should be changed after a series of unauthorized disclosures by a former National Security Agency contractor raised serious questions about secret intelligence programs, including the collection of millions of Americans' phone records.

Senate Intelligence Committee Chairman Dianne Feinstein, D-Calif., opening a new round of public hearings on the matter, said that while she believed the programs are "lawful and effective,'' she was nevertheless preparing a legislative proposal that would limit access to the NSA's massive phone record database. The proposal also would likely cut the time that the records could be stored, which now stands at five years.

"It is up to you to lay out the case and set the record straight,'' Feinstein said, referring to top intelligence officials who also testified Thursday in defense of the government's operations. Among them, NSA Director Keith Alexander, who partly blamed inaccurate media reporting for undermining public trust in the programs.

Georgia Sen. Saxby Chambliss, the panel's ranking Republican, said that "mistakes'' have been made within the intelligence collection system, but he believed there had been "no intentional abuse.'' Yet he signaled that he would join Feinstein in an attempt to make the programs more transparent.

Director of National Intelligence James Clapper, meanwhile, reasserted his defense of the programs, saying that "we don't spy on anyone except for valid foreign intelligence purposes.''

But he also acknowledged growing public "concerns'' about the government's surveillance tactics in the wake of a series of disclosures by former NSA contractor Edward Snowden. And Clapper expressed a readiness to "adjust'' the programs in an attempt to restore flagging public trust.

Clapper suggested that some agreement might be reached on the appointment of an independent advocate for privacy and civil liberties issues that could vet government requests for information made to the Foreign Intelligence Surveillance Court, which now rules on the secret requests submitted by the government.

"If we don't have the trust of the American people, all is for naught,'' Clapper told the panel.

Trust - or lack of it - in the surveillance system was a persistent theme in Thursday's hearing where some lawmakers appeared to struggle with how to restore credibility to a system whose workings have been largely secret until Snowden's disclosures during the summer.

"We have to acknowledge that a whole lot of American people have lost trust in what you are doing,'' Sen. Mark Warner, D-Va., told the intelligence officials assembled before the panel.

Sen. Dan Coats, R-Ind., like the NSA director, blamed media accounts for misrepresenting the government operations.

"People refuse to look at the facts,'' Coats said. "It's very frustrating.''

Sen. Ron Wyden, D-Ore., one of the leading critics of the mass phone record collection program, blamed government leaders for constructing "a system that deceived the American people.''

Wyden and three other senators unveiled a proposal Wednesday that would end the sweeping authority for mass collection operations.

Under the proposal, also supported by Democrats Mark Udall of Colorado and Richard Blumenthal of Connecticut, and Republican Rand Paul of Kentucky, the government could access telephone and Internet records only of those suspected of terrorism or espionage.

The bill also would require a civil-rights advocate to be present during the secret Foreign Intelligence Surveillance Court proceedings, a provision similar to one that Clapper appeared to support.

Thursday's Senate hearing is to be followed next week by a similar debate in the House.